This experiment was designed to study the influences of age and nursing on the energy expenditure of grazing Japanese Black Breed of Cattle.
Three lots of cow were used ; 3 old, 3 prime and 3 prime nursing cows.
The heat production was calculated indirectly by using the regression formula (discussed in the previous report) from the typical pulse rate in each behavior observed.
The principal results are as follows :
1. Heat output was about 36.8 Cal. per kg. per day in average, and prime cow nursing produced the largest quantity of heat and old cow the smallest.
2. Daily heat production was about 13,000～14,000 Cal. per head, and this value is seems to be higher as usual on this range.
3. Daily heat production was consisted mostly of grazing form (40～45%), ruminating form (about 25%) and resting form (17-23%). The energy expenditure in migrating form (4-7%), loafing form (3-6%) and nursing form (about 2.5%) were very little. Prime cow nursing spent about 70% of her energy on grazing and ruminating, and her resting time (about 19%) was comparatively short.
4 . Grazing cow walked about 6 or 7 km a day, but the distance was greatly varied individually - from 3 to 13 km. Generally, prime cow seems to walk longer distance than old one.
In conclusion, as the energy expenditure of grazing cattle is considerably larger than that of those confined to the barn, in the case of determine the range area, stocking rate and grazing period, we must investigate the condition of grassland and determine the ideal grazing scale and method which keep the balance in energy intake and expenditure of grazing animal, under consideration of its age and other conditions.